The present invention relates to precision electrical measurement devices and in particular to a method for providing component connection points having very low dielectric absorption in such devices.
In devices for measuring very low currents (e.g., nanoamperes and below), conventional printed circuit board designs absorb unacceptable numbers of electrons or other charge carriers at the low current nodes of the devices. This absorption is referred to as dielectric absorption.
In order to overcome this limitation, holes are drilled in the board and standoffs are inserted. The standoffs are made of materials such as sapphire or Teflon plastic that have the desired low dielectric absorption. As shown in FIG. 1, the standoff 1 is typically provided with a soldering post 2. Leads 3, 4 from the components to be connected are soldered to the post 2. The standoff 1 prevents unacceptable levels of charge or current from moving between the post 2 and the printed circuit board 5.
In addition to the expense of the standoffs themselves, this technique has the serious disadvantage that the connections have to be hand soldered and cleaned. This creates substantial cost increases over flow soldering. Also, the use of standoffs interferes with ability to shrink overall device size as components are miniaturized and/or integrated.